BIOMECHANICS (PART3) Flashcards
what is Biomechanics ?
Biomechanics is the study of human movements, the effect of force and motion on a sport performance.
What are Newton’s laws?
Law of inertia, Law of acceleration and Law of reaction.
What is stated in Newton’s first law?
Law of inertia, A body remains at rest or uniform velocity until an external or unbalanced force acts upon it.
What is stated in Newton’s second law?
Law of acceleration, A body’s rate of change in momentum is proportional to the size of force applies and acts in the same direction as the force applies.
What is stated in Newton’s third law?
Law of Reaction, when 2 body’s come into contact with each other there is an equal and opposite reaction force.
What are the 4 different concepts that can be calculated?
Velocity, Momentum, Acceleration, force.
What is the formula for Velocity and Momentum?
Velocity=displacement/time taken
Momentum=Mass X Velocity
What is the formula for Acceleration and Force?
Acceleraration= (final velocity - initial velocity)/time taken
What are the units for the 4 main concepts that can be calculated?
Velocity= m/s
momentum= kgm/s
Acceleration= m/s/s
Force= Newtons (N)
what is force and its doing?
Essential for motion, external and internal forces act on a body that tend to alter a body’s state of motion.
External force?
is an outside force that acts on the body, e.g. friction, air resistance, weight (gravity), reaction.
Internal force?
Generated from within the body, when the skeletal muscle contract .
example; (100m sprinter contracts rectus femoris to extend knee and gastrocnemous to planter flex the ankle to generate force needed to drive away).
What is Net force and when is Net force = 0?
Net force is the overall motion of the body taking HORIZONTAL and VERTICLE forces into count. Net force = 0 when the overall motions have no change in it and all force are balanced.
When is Net force unbalanced?
Net force is unbalanced when there is change in motion and the external force acting on a body are unbalanced. During this situation of a body there will be acceleration, deceleration, change in shape and direction.
Example of when Net force is balanced and unbalanced.
Net force balanced; in rugby 2 packs are in scrum with equal weight(Net force = 0)
Net force unbalanced; in tennis serve the player generates greater force then needed to over come the tennis ball’s inertia.
how does Analysis through use of technology help sports?
professionals uses it to analyse movement and enhance performance.
What is Limb Kinematics?
Is the study of movements in relation to time and space.
How does Limb kinematics analyse’s movements.
reflective markers are placed on the body’s joints to which can be traced by the infra-red camera’s and convert into digital format. To evaluate the joint and limb efficiency with measurements of bones geometry, displacement, velocity and acceleration in multiple planes of movements.
Disadvantages of limb kinematics.
too expensive.
doesn’t account for individual difference.
Limited to lab conditions
Advantages of Limb kinematics?
Immediate anaylsis recieved
abjective measurements
accurate data
What is force plate?
It can measure ground reaction force of athletes, balancing, running or jumping.
uses transducers to measure the force involved in during motion.
How does force plates work?
upon coming into contact with force plate it will display the time and force that is being applied on a graphical form of computer..
Advantages of force plates?
Reliable results are provided.
Can prevent injuries
Helps with generating the force needed for every contact point e.g. in verticle jump both legs need to generate the same Newtons of force.
Disadvantages of force plate?
Too expensive
limited to lab conditions
maintenance/specialist training required.
What is Reliability?
the extent to which an experiment, test, or measuring procedure gives the same result after repeated trails.
What is validity?
How well a test measures what it claims to measure.
What is Validity and Reliability purpose?
The purpose of establishing reliability and validity in research is essentially to ensure that data are sound and replicable, and the results are accurate.
What are Wind tunnels?
Are aerodynamic tunnels that help to improve the the movement of air around an object e.g. F1 car.
Advantages of Wind tunnels?
Accurate and Reliable data,
Good for performance analysis,
Can control environmental variables.
Disadvantages of wind tunnels?
Very expensive to buy.
Take lots of space due its size.
Needs specialists to function it.
The analysis are very complex.
Center of mass definition.
Centre of is the point at which the forces are balanced in all directions or from where gravity acts from
Stability definition.
The ability for a body to resist motion and remain at rest.
+
It is also the ability to withstand applied force and return to original position.
factors that effect stability.
Mass of Body,
Height of centre of mass
Base of Support,
Line of Gravity
How can unstability be advantagous.
Changing direction,
Rotating,
Increasing the range of motion or stretching
How to minimise stability?
Stability is minimised when the force acting on body are unbalanced and the body has gained motion.
How to maximise stability?
Low body position (gives low centre of mass)
Large Base of support
Having multiple contact points
Line of gravity close to Base of support
Larger mass
What is Lever system?
Is the co-ordination of our bones and muscles, to create human movement.
Function of lever system?
Generate muscular effort to overcome a given load
Increase the speed of a given movement
Name the 4 components of Lever System.
Lever=Bone
Fulcrum=Joint
Load=weight or resistance
Effort=muscular force
What is a Lever?
A rigid structure which rotates around a fixed point.
what is the fixed point where the Lever rotates?
fulcrum(joints)
when is effort created?
when the muscles surrounding the joint contracts and the force is generated.
Why is the force needed?
To overcome a given load.
Example of Lever;
Radius and Ulna
Example of Fulcrum;
Elbow joint
Example of Effort;
Force created by biceps brachii
Example of Load;
holding weights in hand during bicep curls
Classification of levers
First class levers
Second class levers
Third class levers
components and example of first class lever;
COMPONENT; fulcrum is in the middle
* E - F - L or L - F - E
EXAMPLE
extention of the head when preparing to header the ball
components and example of Second class lever;
COMPONENT; Load is in the middle
* F - L - E or E - L - F
EXAMPLE
Ball of the foot in the take off phase of high jump
components and example of third class lever;
COMPONENT; Effort is in the middle
* F - E - L or L - E - F
EXAMPLE
Flexion of the elbow during bicep curl
Efficiency of the lever system is the……(what?)
is the order and distance of lever components from the fulcrum;
*Distance of Fulcrum > Effort == Effort arm
*Distance from Load > Fulcrum == Load arm
What give a lever system Mechanical advantage or Mechanical disadvantage?
The length of the Effort or Load arm.
True or False
in second class lever the effort arm is always greater than the Load arm.
True
What Mechanical Advantage? which class lever has it?
Mechanical advantage is where the Effort arm is greater than the Load arm.
*Second class lever
What Mechanical disadvantage? which class lever has it?
Mechanical disadvantage is where the Load arm is greater than the Effort arm.
*Third class lever
What does Mechanical Advantage do?
Allows you to move larger load with relatively small force.
What does Mechanical disadvantage do?
Larger Effort is required to move relatively small load.
positive and negative of Second class lever or Mechanical advantage;
Positive;
*larger load is moved with small force
negative;
*at the expense of velocity
positive and negative of third class lever or Mechanical disadvantage;
positive;
*moves the load at high velocity
*generate greater acceleration over larger range of motion
Negative;
*Need greater effort than load
